Cutting aluminum?

[Larry Edgerton]

I have had two motorhomes self destruct due to nature taking its toll on poor design/construction so have decided to build one. I bought a 1983 Grumman-Olson step van with an aluminum body. The sheet stock is 1/8" thick, and I have six windows to install. Flanges are relatively small so it needs to be pretty precise. I don't want to cut it with a jig saw if I can help it, can't find a nibbler that will cut stock that thick, plus the rivets may be a problem.
I would like to do it with a router and a jig but have never cut aluminum with a router. The windows have a 2.5 inch radius corner so a router would be fine. But..........

Its not like you get a second chance when doing the side of a vehicle so am a bit apprehensive.

Lets hear your suggestions based on experience.

Thanks, Larry

[Dennis Peacock]

Hello Larry,
I'd use a good jigsaw to cut "close" to where you need it to be and then use a good quality carbide router bit and a properly setup router jig to finish the cuts to final dimension. I've used my variable speed router on it's slowest speed to trim aluminum sheet before. It can be a bit loud, so wear good eye and ear protection. A good carbide bit, jig, and slow controlled movement with the router would yield you good results. So there, just my experience and nothing more...so your mileage may vary.

[Cody Colston]

I second what Dennis said. I would also recommend a face shield in addition to safety glasses.

[Larry Edgerton]

Thanks gentlemen. That is actually the method I had in mind but wanted to hear from someone that has done it.

Its kind of intimidating as I am ruining the value of the vehicle as a commercial truck, and I want to do it right. The windows are 22" wide and the stud spacing is 24" so they just sneak in between the aluminum studs, and barely miss the rivets. Placemant has to be within 1/16". I thought about bigger windows but decided to not cut the studs as the whole idea of this rig is to be indestructible.

[mike holden]

Larry, the very first time I used a router was in a pattern shop and the job was to trim 3/4 inch thick aluminum panels glued to a fiberglas "splash" to make a drill fixture for an aircraft wing. Carbide trim bit and aluminum flakes everywhere. We did the job wearing tyvek jumpsuits in the spray booth. Worked just fine.
Mike

[John Blazy]

All above is great advise, but missing the most important part - cutting fluid. it makes a HUGE difference. if you cant get spray Tap Magic, then even WD 40 works great on aluminum, whether T-saw cutting, Jig saw (seems best for this job), or slowed down router cutting. Slowest speed possible with any cutter you use. IF you mark a line and plan to jig saw cut, spray on the underside of the alum where the cut will be, as well as the blade. If you have a helper, they can spray as you cut.

I bought a solid carbide 1/2" tight spiral bit made for aluminum. Its spiral is like one full revolution in 1/2", super shearing cut. Its such a cool pc of machining, I hate to use it.

[pat warner]

Working on a vertical surface with a 10 pound router will be a hell of challenge.
I cut/rout aluminum (totally cut with routers), when the work is horizontal.
If the thickness is>1/4", plan on stage plunge routing.
I don't envy you, this job.

[John K Jordan]

I cut openings for ventilation in the sides and top of an all-aluminum shipping container. The aluminum sides are about 1/8" thick. I drilled a hole and used a sawzall for all the openings. Was real quick.

JKJ

[Rick Fisher]

I just ripped 1.6mm in 4x8 sheets.. It was aluminum checkerplate.. I cut it on a table saw with a 60 tooth blade. I used tape on the spots I would cut and wore a turners mask .. the chips come flying at you and actually hurt .. lol ..

Without tape, its war.. chips bouncing off your face .. ugh .. with tape and a face shield .. its no big deal. 1/8" thick .. that would be slower.

[Wayne Lomman]

John Blazy is right. Cutting fluid or wax lube is an absolute must. All of you cutting aluminium with carbide tooling are at extremely high risk of wearing broken cutters. Without lubricant the aluminium builds up on the cutter until it breaks the teeth.
Also note that conventional wood saw blade geometry is incorrect for aluminium which is why some of you are wearing shrapnel. Do some research with a tooling supplier. Cheers

[John K Jordan]

John Blazy is right. Cutting fluid or wax lube is an absolute must. All of you cutting aluminium with carbide tooling...

Just to be clear, aluminum+carbide+lube, yes. aluminum+bimetal saw blade, maybe not so much. The aluminum plate I cut with a sawzall was with no lube.

Aluminum with HSS cutter on the mill, a bit of lube. Aluminum with 10V spindle gouges on the wood lathe, no lube.

I've always heard just don't machine aluminum with carbide cutters. Next time I'll try a carbide end mill with some lube and see how it works.

JKJ

[John McClanahan]

The grade (alloy) of aluminum will influence the cutting quality. I don't know how to tell a piece of aluminum by looking ay it, but when I cut it on my table saw sometimes it boots good and other times metal sticks to the saw teeth, or bit in your case. That's when the trouble starts. Of you can't use oil, even some soapy water in a spray bottle helps a lot.


John

[Dennis Ford]

The grade (alloy) of aluminum will influence the cutting quality. I don't know how to tell a piece of aluminum by looking ay it, but when I cut it on my table saw sometimes it boots good and other times metal sticks to the saw teeth, or bit in your case. That's when the trouble starts. Of you can't use oil, even some soapy water in a spray bottle helps a lot.


John

This is exactly right, some aluminum does not require lube and some can almost not be cut without lube. It all looks about the same, does not mean that it is the same.

[Larry Edgerton]

Working on a vertical surface with a 10 pound router will be a hell of challenge.
I cut/rout aluminum (totally cut with routers), when the work is horizontal.
If the thickness is>1/4", plan on stage plunge routing.
I don't envy you, this job.

My current plan is to cut it out roughly with a jigsaw close to the line and trim to a pattern with the smallest Festool plunge on the lowest speed, the Festool being much lighter than the big Porter Cable plunge. The Porter Cable is not variable speed, another issue. I figure with a plunge it will be easy to keep lowering the bit as it gets buildup. I would like to use a spiral bit but the Festool will not accept 1/2". Will do a test today.

I have a plasma cutter, but am afraid of it warping the panel that is left on the truck.

[Jerome Stanek]

My current plan is to cut it out roughly with a jigsaw close to the line and trim to a pattern with the smallest Festool plunge on the lowest speed, the Festool being much lighter than the big Porter Cable plunge. The Porter Cable is not variable speed, another issue. I figure with a plunge it will be easy to keep lowering the bit as it gets buildup. I would like to use a spiral bit but the Festool will not accept 1/2". Will do a test today.

I have a plasma cutter, but am afraid of it warping the panel that is left on the truck.

I cut a lot of fiber glass with ridges and find that if I lower the bit all the way on the first cuts then move the bit up works better as the ridges dull the bit quicker